[Monoamine oxidase activity and ultrastructure of subcellular fractions of the cerebral cortex under normal conditions and in the presence of phenamine stimulation].

Crude mitochondrial fractions were fractionated into purified mitochondria, heavy- and light synaptosomes and synaptosomal membranes. The highest MAO activity was observed in purified mitochondria and heavy synaptosomes. Amphetamine strongly inhibited the MAO activity in heavy synaptosomes, and only slightly affected light synyptosomes. Electron microscopy of heavy synaptosomes revealed specific vesicles suggesting the presence of nerve endings of monoaminergic neurons, and the increase of the functional activity of these neurons.